Antarctic sub to test waters for Jupiter moon mission

时间:2019-03-01 07:05:01166网络整理admin

By Kathleen M Wong, San Francisco A robotic submarine designed to explore the oceans thought to lie beneath the icy crust on Jupiter’s moon Europa will prove its mettle in an Antarctic lake in 2008. A previous version of the vessel has already mapped the balmier waters of a Mexican sinkhole. The submarine, named Endurance, is set to survey Antarctica’s West Lake Bonney in October 2008 and again in 2009, scientists reported on Thursday at a meeting of the American Geophysical Union in San Francisco, California, US. The 4-kilometre-wide lake is 40 metres deep and is capped by a perennial layer of ice about 4 metres thick. The crust has kept the lake’s waters pristine and virtually unexplored. Hot water drills will bore a hole for Endurance to enter the water. Once beneath the ice, the sub will gather data for a 3D map of the lake and the submerged face of its adjacent glacier. At the same time, it will sample the frigid waters for signs of life. West Lake Bonney should prove a rigorous test of the submersible’s ability to function on Europa. Once released, Endurance will navigate on its own for up to eight hours at a time – a crucial requirement, since sending radio commands to the distant, icy moon from Earth would take about half an hour. “Europa’s far enough away where you’re not going to be able to drive it like a video game,” says lead investigator Peter Doran of the University of Illinois in Chicago, US. “The robot would need a fair amount of its own intelligence to make its own decisions. With Endurance, we’re at that point.” At the lake, Endurance will follow a pre-programmed path just beneath the ice. “This is so we don’t disturb the environment we’re studying with the robot’s propellers,” Doran says. Instead, the sub will stop and lower a package of scientific instruments into the water column. These will measure water temperature, salinity, turbidity, dissolved organic carbon, and scan for chlorophyll. Together, these measurements should be enough to detect the presence of life. And life may not be so unlikely on Europa. Data from NASA’s Galileo spacecraft has revealed hints of carbon – a building block of life – in the moon’s purported seas. Both carbon dioxide and sulphur dioxide, a potential signal of volcanism, are leaking from discrete areas on the moon’s surface. Operating a spacecraft at Europa may also be easier than originally thought because radiation on the moon is low enough to operate a probe there for a year or more, says William McKinnon of Washington University in St Louis, Missouri, US. Still, many hurdles remain before an underwater vehicle will get to tackle otherworldly seas. At present, Endurance is too massive to send on interplanetary travel. Scientists must also devise a means to drill through Europa’s icy crust and lower the sub safely through the ice. And because radio waves travel poorly through water, a docking station anchored in or around the ice will need to relay data from the submersible to Earth. No one has even begun working on such a transmitter, not least because they need a better understanding of Europa’s ice crust first. According to McKinnon, an orbiter mission to Europa would need to pave the way before any submersible left the launch pad. Using radar, such a spacecraft could measure ice depth, look for convection cells, and perhaps even detect plumes of volcanic activity in addition to demonstrating the presence of liquid water. NASA has committed to launching a mission to one of the icy moons of Jupiter or Saturn sometime between 2015 and 2020. The target of that mission, however, is still being decided. According to Curt Niebur of NASA, the space agency has just completed studies of missions to Jupiter’s moons Europa and Ganymede and Saturn’s moons Titan and Enceladus. NASA plans to announce which missions have been selected for further study in mid-January 2008. Astrobiology – Learn more in our out-of-this-world special report. More on these topics: